Methods and devices for adjusting resource management procedures in heterogeneous communication networks

ABSTRACT

Devices and methods for adjusting resource management procedures in heterogeneous communication networks are disclosed. In one aspect, a method for adjusting radio resource management procedures in a mobile device communicating with a node operating in a cell in a heterogeneous communication network includes receiving a message that includes cell information transmitted from the node, measuring signal reception information, processing the received cell information and measured signal reception information to determine an adjustment to a resource management procedure, and adjusting the resource management procedure based on the determined adjustment. The first and second messages may be radio resource control (RRC) measurement control messages.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority, under 35 U.S.C. §120, to and isa continuation of U.S. patent application Ser. No. 13/420,116, entitled“Methods and Devices for Adjusting Resource Management Procedures inHeterogeneous Communication Networks,” filed Mar. 14, 2012. The presentapplication also claims priority, under 35 U.S.C. §119(e), to U.S.Provisional Patent Application No. 61/599,038, entitled “Enhanced RadioResource Management in HetNets,” filed Feb. 15, 2012. The contents ofeach of the above-referenced applications are incorporated herein byreference in their entirety.

TECHNICAL FIELD

The present invention relates generally to heterogeneous communicationnetworks, and more particularly, to methods and devices for adjustingresource management procedures in heterogeneous communication networks.

BACKGROUND

Currently, the deployment of heterogeneous networks (HetNets) is viewedas one of the most cost efficient deployment strategies for wirelesscommunication systems in addressing the growing traffic demands and theexpectation for higher data rates. Typical cellular networks today arecharacterized by non-uniform user and traffic distributions. HetNetscomplement the macro networks with low power nodes (LPN), such as micro,pico, and femto base stations or relay nodes, which can achievesignificantly improved capacity and high data rates.

In wireless communication systems with a heterogeneous networkdeployment, mobility management is a challenging task. Investigationshave been undertaken to evaluate performance of hard handover inorthogonal frequency-division multiplexing (OFDM) based cellularsystems, such as 3GPP Long-Term Evolution (LTE) or IEEE 802. Systemlevel simulation results have been extensively discussed withinstandardization, such as 3GPP. Simulation results from these studiesshow that the careful choice of handover triggers (i.e., Time-to-Triggerand signal hysteresis) for cells of different sizes can lead tosubstantial reduction in handover failure rate, as well as system andservice performance improvements.

In wireless communication systems with a heterogeneous networkdeployment, it is important to choose the optimal mobility trigger touse when a mobile device or other user equipment (UE) is operating indifferent types of cells, e.g. different mobility triggers should beused when the UE is operating in a macro cell, as compared with when theUE is operating in a femto cell. Failure to use the optimal mobilitytrigger in such systems can be more severe than in normal networksfeaturing uniform deployment of cells. For example, with a largeTime-to-Trigger in a macro cell, the handover might be delayed, whichmeans that the communication with the serving base station is verylikely experiencing higher loss rate and, thus, a higher probability ofradio link failure. In addition, this communication interferes with themicro, pico or femto base station eNodeB (eNB) or low power node (LPN)in uplink, and in downlink, UEs served by LPNs and located close tosmall cell's borders are heavily interfered with by the transmissions tothe UE still connected to the macro base station (eNB). Theseinterference effects are more pronounced and more troublesome for anoperator in a wireless communication system with a heterogeneous networkdeployment, than in a homogeneous network.

Currently, the cell selection and handover functionality in LTE iscontrolled by the network. While the UE provides measurements to thenetwork (i.e., eNB), the UE is unable to influence or responddynamically to perform optimized handover decisions. The handovertriggers, as well as additional mobility related parameters, such asLayer 3 filtering coefficients and measurement bandwidth, are configuredby the eNB and transmitted to the UE via measurement control messages.The UE uses the configured parameters to evaluate the configured events,e.g., the cell reselection is implicitly controlled by the network.

One drawback for this conventional method is that the measurement reportfrom the UE is a L3 filtered value of reference signal received power(RSRP)/reference signal received quality (RSRQ), which does notrepresent the current real-time link quality as a result of filteringand because there is a time delay between when the UE measures RSRP/RSRQand when the measurements are available at the serving eNB. This timedelay can range from few msecs up to hundreds of msecs. Moreover, theUE, once it has reported RSRP/RRSQ to the network, has to wait during agiven time period before the UE can report updated RSRP/RSRQ values tothe network. This time period is on the order of a few hundreds ofmsecs.

In wireless communication systems with a heterogeneous networkdeployment, more up-to-date real-time measurements, which can reflectthe current radio link quality, are needed in order to optimize thehandover procedure. One reason for this is that smaller cell sizeinvolves more dynamic signal strength changes. It is not a viablesolution for the eNB to obtain real-time measurements from the UE sincethis would result in consuming a significantly high amount of UEresources. Further, as discussed above, the cell selection and handoverfunctionality in LTE is controlled by the network, and although the UEprovides measurements to the network (i.e., eNB), the UE is unable toinfluence or respond dynamically to perform optimized handoverdecisions.

Considering cell size as part of adapting mobility related parametersleads to mobility performance improvements. More specifically, it hasbeen discussed within 3GPP that different mobility triggers should beused when the UE is located in a large cell, as compared with when theUE is located in a small cell. The UE, however, even with thesedifferent mobility triggers, is unable to determine which sets oftriggers to use since the UE is not aware of the cell size within itscurrent cell, unless instructed by the network. It is noted that, in3GPP TS 36.423, the Cell Type IE, which contains the information of cellsize (very small, small, medium, large), is included in the Last VisitedCell IE in the UE History Information IE, and is included in the SourceeNB to Target eNB Transparent Container IE in the Handover Requestmessage over S1. However, this information (i.e., cell type/cell size)is only exchanged among the networks, and the UE does not have anyinformation on cell type and cell size.

Accordingly, there is a need for a method and device for adjusting radioresource management procedures in wireless communication systems with aheterogeneous network deployment that can improve system and serviceperformance by optimizing handover procedures, decreasing the handoverfailure rate, and by improving radio resource management such as uplinkpower control, radio link failure and link adaptation.

SUMMARY

Particular embodiments of the present invention are directed to devicesand methods for adjusting resource management procedures inheterogeneous communication networks.

In one particular aspect, a method for adjusting resource managementprocedures in a mobile device communicating with a node operating in acell in a heterogeneous communication network includes transmitting afirst message to the node. The first message includes a request for cellinformation. The method further includes receiving a second messagetransmitted from the node. The second message includes the requestedcell information. The method further includes measuring signal receptioninformation, processing the received cell information and measuredsignal reception information to determine an adjustment to a resourcemanagement procedure, and adjusting the resource management procedurebased on the determined adjustment.

According to particular embodiments of the present invention, the firstmessage and the second message are radio resource control (RRC)messages. In some embodiments, the first message is a radio resourcecontrol (RRC) connection request message and the second message is aradio resource control (RRC) connection response message.

In some embodiments, the cell information includes information relatingto one or more of cell size, cell type, system load, node information,maximum transmit power, maximum base station users, number of antennasand antenna gain, and the signal reception information includesinformation relating to one or more of reference signal received power(RSRP), reference signal received quality (RSRQ), channel qualityindicator (CQI), channel state information (CSI), and signal tointerference plus noise ratio (SINR). More generally, however, the cellinformation may include or represent any appropriate informationrelating to the characteristics or configuration of the relevant celland/or a base station serving the cell. Furthermore, the signalreception information may, more generally, include or represent anyappropriate information relating to signal strength, channel quality, orother properties of the signals received by the mobile device or thechannel over which the mobile device receives such signals.

In some embodiments, adjusting the radio resource management procedureincludes adjusting one or more of handover, uplink (UL) power control,radio link failure (RLF) recovery and link adaptation. Additionally, inembodiments in which the handover procedure is adjusted, the adjustmentmay include, for example, setting the size of the measurement report,setting the value of measurement gap, determining a Time-to-Triggervalue, or determining a signal hysteresis value. In embodiments in whichRLF recovery procedures are adjusted, the adjustment may include, forexample, determining a particular cell with respect to which the mobiledevice will perform the RLF recovery. In embodiments in which linkadaptation procedures are adjusted, the adjustment may include, forexample, adjusting a frequency with which reference signals (such asSounding Reference Symbols (SRSs)) or channel information (such asChannel Quality Information (CQI)) are communicated between the mobiledevice and network, or adjusting a modulation and/or coding schemeconfiguration for the mobile device. In embodiments in which powercontrol is adjusted, the adjustment may include, for example, setting aspecific transmission power used by the mobile device or changing theprocedure for setting the transmission power (e.g., by changing a sizeof the incremental power control steps applied by the mobile device whendetermining an appropriate transmission power).

In some embodiments, the method further includes measuring a valuerelating to a radio channel quality for transmitting to the node andtransmitting the first message to the node only when the measured valueis greater than a predetermined threshold value.

Particular embodiments provide a mobile device operable in aheterogeneous communication network to transmit messages to and receivemessages from a node operating in a cell. According to certainembodiments of the present invention, the mobile device includes aprocessor, a memory coupled to the processor, a transceiver coupled tothe processor, and an antenna coupled to the transceiver configured totransmit and receive messages. In some embodiments, the processor isconfigured to transmit a first message to the node. The first messageincludes a request for cell information. The mobile device may beconfigured to receive a second message transmitted from the node. Thesecond message includes the requested cell information. The mobiledevice may be configured to measure signal reception information,process the received cell information and measured signal receptioninformation to determine an adjustment to a resource managementprocedure, and adjust the resource management procedure based on thedetermined adjustment.

According to particular embodiments of the present invention, the firstmessage and the second message are radio resource control (RRC)messages. In some embodiments, the first message is a radio resourcecontrol (RRC) connection request message and the second message is aradio resource control (RRC) connection response message.

In some embodiments, the cell information includes information relatingto one or more of cell size, cell type, system load, node information,maximum transmit power, maximum base station users, number of antennasand antenna gain, and the signal reception information includesinformation relating to one or more of reference signal received power(RSRP), reference signal received quality (RSRQ), channel qualityindicator (COI), channel state information (CSI), and signal tointerference plus noise ratio (SINR).

In some embodiments, adjusting the radio resource management procedureincludes adjusting one or more of handover, uplink (UL) power control,radio link failure (RLF) recovery and link adaptation, and may includeany of the example adjustments described above and/or other suitableadjustments.

In some embodiments, the processor may be further configured to measurea value relating to a radio channel quality for transmitting to the nodeand to transmit the first message to the node only when the measuredvalue is greater than a predetermined threshold value.

In another particular aspect, a method for adjusting resource managementprocedures in a mobile device communicating with a node operating in acell in a heterogeneous communication network includes receiving a firstmessage from the mobile device. The first message includes a request forcell information. The method further includes measuring a value relatingto received signal strength and transmitting a second message to themobile device only when the measured value is greater than apredetermined threshold value. The second message includes the requestedcell information.

According to particular embodiments of the present invention, the firstmessage and the second message are radio resource control (RRC)messages. In some embodiments, the first message is a radio resourcecontrol (RRC) connection request message and the second message is aradio resource control (RRC) connection response message.

In some embodiments, the cell information includes information relatingto one or more of cell size, cell type, system load, node information,maximum transmit power, maximum base station users, number of antennasand antenna gain.

Particular embodiments provide a node operable in a heterogeneouscommunication network to transmit messages to and receive messages froma mobile device operating in a cell. According to particular embodimentsof the present invention, the node includes a processor, a memorycoupled to the processor, a network interface coupled to the processor,a transceiver coupled to the network interface, and an antenna coupledto the transceiver configured to transmit and receive messages. Theprocessor may be configured to receive a first message from the mobiledevice. The first message includes a request for cell information. Theprocessor may be configured to measure a value relating to receivedsignal strength and to transmit a second message to the mobile deviceonly when the measured value is greater than a predetermined thresholdvalue. The second message includes the requested cell information.

In some embodiments, the first message and the second message are radioresource control (RRC) messages. In some embodiments, the first messageis a radio resource control (RRC) connection request message and thesecond message is a radio resource control (RRC) connection responsemessage.

In some embodiments, the cell information includes information relatingto one or more of cell size, cell type, system load, node information,maximum transmit power, maximum base station users, number of antennasand antenna gain.

In one particular aspect, a method for adjusting resource managementprocedures in a mobile device communicating with a node operating in acell in a heterogeneous communication network includes receiving amessage transmitted from the node. The message includes cellinformation. The method further includes measuring signal receptioninformation, processing the received cell information and measuredsignal reception information to determine an adjustment to a resourcemanagement procedure, and adjusting the resource management procedurebased on the determined adjustment.

According to particular embodiments of the present invention, themessage is a radio resource control (RRC) measurement control message.

In some embodiments, the cell information includes information relatingto one or more of cell size, cell type, system load, node information,maximum transmit power, maximum base station users, number of antennasand antenna gain, and the signal reception information includesinformation relating to one or more of reference signal received power(RSRP), reference signal received quality (RSRQ), channel qualityindicator (CQI), channel state information (CSI), and signal tointerference plus noise ratio (SINR).

In some embodiments, adjusting the radio resource management procedureincludes adjusting one or more of handover, uplink (UL) power control,radio link failure (RLF) recovery and link adaptation, and may includeany of the example adjustments described above and/or other suitableadjustments.

Particular embodiments provide a mobile device operable in aheterogeneous communication network to transmit messages to and receivemessages from a node operating in a cell. According to certainembodiments of the present invention, the node includes a processor, amemory coupled to the processor, a transceiver coupled to the processor,and an antenna coupled to the transceiver configured to transmit andreceive messages. The processor may be configured to receive a messagetransmitted from the node. The message includes cell information. Theprocessor may be configured to measure signal reception information,process the received cell information and measured signal receptioninformation to determine an adjustment to a resource managementprocedure, and adjust the resource management procedure based on thedetermined adjustment.

According to particular embodiments of the present invention, themessage is a radio resource control (RRC) measurement control message.In some embodiments, the cell information includes information relatingto one or more of cell size, cell type, system load, node information,maximum transmit power, maximum base station users, number of antennasand antenna gain, and the signal reception information includesinformation relating to one or more of reference signal received power(RSRP), reference signal received quality (RSRQ), channel qualityindicator (CQI), channel state information (CSI), and signal tointerference plus noise ratio (SINR).

In some embodiments, adjusting the radio resource management procedureincludes adjusting one or more of handover, uplink (UL) power control,radio link failure (RLF) recovery and link adaptation, and may includeany of the example adjustments described above and/or other suitableadjustments.

The above and other aspects and embodiments are described below withreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and form partof the specification, illustrate various embodiments of the presentdisclosure and, together with the description, further serve to explainthe principles of the disclosure and to enable a person skilled in thepertinent art to make and use the embodiments disclosed herein. In thedrawings, like reference numbers indicate identical or functionallysimilar elements.

FIG. 1 illustrates an architecture of a wireless communication systemwith a heterogeneous network deployment, in accordance with exemplaryembodiments of the present invention.

FIG. 2 is a block diagram of a node, as used in the system of FIG. 1 inaccordance with exemplary embodiments of the present invention.

FIG. 3 is a block diagram of a mobile device, as used in the system ofFIG. 1 in accordance with exemplary embodiments of the presentinvention.

FIG. 4 is a time sequence diagram illustrating a first exemplarymessaging flow for a method for adjusting radio resource managementprocedures in a mobile device operating in a heterogeneous communicationnetwork, in accordance with exemplary embodiments of the presentinvention.

FIG. 5 is a diagram of information elements of a radio resource control(RRC) cell information request message for use in a method for adjustingradio resource management procedures in a mobile device operating in aheterogeneous communication network, in accordance with exemplaryembodiments of the present invention.

FIG. 6 is a diagram of information elements of a radio resource control(RRC) cell information response message for use in a method foradjusting radio resource management procedures in a mobile deviceoperating in a heterogeneous communication network, in accordance withexemplary embodiments of the present invention.

FIG. 7 is a flow chart illustrating the steps performed by a mobiledevice in a method for adjusting radio resource management procedures ina mobile device operating in a heterogeneous communication network usingradio resource control (RRC) cell information request and responsemessages, in accordance with exemplary embodiments of the presentinvention.

FIG. 8 is a flow chart illustrating the steps performed by a node in amethod for adjusting radio resource management procedures in a mobiledevice operating in a heterogeneous communication network using radioresource control (RRC) cell information request and response messages,in accordance with exemplary embodiments of the present invention.

FIG. 9 is a time sequence diagram illustrating a second exemplarymessaging flow for a method for adjusting radio resource managementprocedures in a mobile device operating in a heterogeneous communicationnetwork, in accordance with exemplary embodiments of the presentinvention.

FIG. 10 is a diagram of information elements of a radio resource control(RRC) connection request message for use in a method for adjusting radioresource management procedures in a mobile device operating in aheterogeneous communication network, in accordance with exemplaryembodiments of the present invention.

FIG. 11 is a diagram of information elements of a radio resource control(RRC) connection response message for use in a method for adjustingradio resource management procedures in a mobile device operating in aheterogeneous communication network, in accordance with exemplaryembodiments of the present invention.

FIG. 12 is a flow chart illustrating the steps performed by a mobiledevice in a method for adjusting radio resource management procedures ina mobile device operating in a heterogeneous communication network usingradio resource control (RRC) connection request and response messages,in accordance with exemplary embodiments of the present invention.

FIG. 13 is a flow chart illustrating the steps performed by a node in amethod for adjusting radio resource management procedures in a mobiledevice operating in a heterogeneous communication network using radioresource control (RRC) connection request and response messages, inaccordance with exemplary embodiments of the present invention.

FIG. 14 is a time sequence diagram illustrating a third exemplarymessaging flow for a method for adjusting radio resource managementprocedures in a mobile device operating in a heterogeneous communicationnetwork, in accordance with exemplary embodiments of the presentinvention.

FIG. 15 is a diagram of information elements of a radio resource control(RRC) measurement control message for use in a method for adjustingradio resource management procedures in a mobile device operating in aheterogeneous communication network, in accordance with exemplaryembodiments of the present invention.

FIG. 16 is a flow chart illustrating the steps performed by a node in amethod for adjusting radio resource management procedures in a mobiledevice operating in a heterogeneous communication network using a radioresource control (RRC) measurement control message, in accordance withexemplary embodiments of the present invention.

FIG. 17 is a flow chart illustrating the steps performed by a mobiledevice in a method for adjusting radio resource management procedures ina mobile device operating in a heterogeneous communication network usinga radio resource control (RRC) measurement control message, inaccordance with exemplary embodiments of the present invention.

DETAILED DESCRIPTION

In exemplary embodiments of the disclosed methods and devices, a methodfor adjusting radio resource management procedures in a mobile devicecommunicating with a node operating in a cell in a heterogeneouscommunication network is described. In the methods and devices describedherein, radio resource management procedures in a mobile device areadjusted to, for example, optimize handover and improve uplink powercontrol, radio link failure and link adaptation, based on cellinformation received from the node and signal reception informationmeasured by the mobile device. This combined information, whichincludes, for example, information on cell size and cell type receivedfrom the node, and real-time RSRP and RSRQ values measured by the mobiledevice, enables the mobile device to adjust one or more aspects of theradio resource management procedures utilized by the mobile device. Forexample, the mobile device may set the size of a measurement report, setthe value of measurement gap, determine a Time-to-Trigger value anddetermine a signal hysteresis value, to optimize handover or adjustaspects of its uplink power control, radio link failure and linkadaptation, as described in further detail below.

Referring now to FIG. 1, an architecture of a wireless communicationsystem 100 with a heterogeneous network deployment, in accordance withexemplary embodiments of the present invention, is illustrated. Asshown, wireless communication system 100 includes a wireless network105, nodes 110 and 115, and mobile devices 120. Examples of node 110include base stations and relay nodes, such as, for example, servingeNodeB (eNB), high power, and macrocell base stations and relay nodes.Examples of node 115 include base stations and relay nodes, such as, forexample, low power, micro, pico, and femto base stations and relaynodes. Examples of mobile devices 120 include wireless User Equipment(UE) and communication devices, such as, for example, mobile telephones,personal digital assistants, electronic readers, portable electronictablets, personal computers, and laptop computers.

Referring now to FIG. 2, a block diagram of nodes 110 and 115, as usedin the system of FIG. 1 in accordance with exemplary embodiments of thepresent invention, is illustrated. As shown in FIG. 2, node 110 and 115may include: a data processing system 220, which may include one or moremicroprocessors and/or one or more circuits, such as an applicationspecific integrated circuit (ASIC), Field-programmable gate arrays(FPGAs), and the like; network interface 215; and a data storage system225, which may include one or more non-volatile storage devices and/orone or more volatile storage devices (e.g., random access memory (RAM)).The network interface 215 is connected to transceiver 210, which isconfigured to transmit and receive signals via an antenna array 205. Inembodiments where data processing system 220 includes a microprocessor,computer readable program code may be stored in a computer readablemedium, such as, but not limited, to magnetic media (e.g., a hard disk),optical media (e.g., a DVD), memory devices (e.g., random accessmemory), and the like. In some embodiments, computer readable programcode is configured such that, when executed by a processor, the codecauses the data processing system 220 to perform steps described below(e.g., steps described below with reference to the flow charts shown inFIGS. 8, 13 and 16). In other embodiments, the nodes 110 and 115 areconfigured to perform steps described above without the need for code.That is, for example, data processing system 220 may consist merely ofone or more ASICs. Hence, the features of the present inventiondescribed above may be implemented in hardware and/or software. Forexample, in particular embodiments, the functional components of thenodes 110 and 115 described above may be implemented by data processingsystem 220 executing computer instructions, by data processing system220 operating independent of any computer instructions, or by anysuitable combination of hardware and/or software.

Referring now to FIG. 3, a block diagram of a mobile device, as used inthe system of FIG. 1 in accordance with exemplary embodiments of thepresent invention, is illustrated. As shown in FIG. 3, mobile device 120may include: a data processing system 315, which may include one or moremicroprocessors and/or one or more circuits, such as an applicationspecific integrated circuit (ASIC), field-programmable gate arrays(FPGAs), and the like; a transceiver 310 for transmitting data to (andreceiving data from) nodes 110 and 115 via antenna array 305; and amemory 320, which may include one or more non-volatile storage devicesand/or one or more volatile storage devices (e.g., random access memory(RAM)). In embodiments where data processing system 315 includes amicroprocessor, computer readable program code may be stored in acomputer readable medium, such as, but not limited, to magnetic media(e.g., a hard disk), optical media (e.g., a DVD), memory devices (e.g.,random access memory), and the like. In some embodiments, computerreadable program code is configured such that when executed by aprocessor, the code causes mobile device 120 to perform steps describedbelow (e.g., steps described below with reference to the flow chartsshown in FIGS. 7, 12 and 17). In other embodiments, mobile device 120 isconfigured to perform steps described above without the need for code.That is, for example, data processing system 315 may consist merely ofone or more ASICs. Hence, the features of the present inventiondescribed above may be implemented in hardware and/or software. Forexample, in particular embodiments, the functional components of mobiledevice 120 described above may be implemented by data processing system315 executing computer instructions, by data processing system 315operating independent of any computer instructions, or by any suitablecombination of hardware and/or software.

Referring now to FIG. 4, a time sequence diagram 400 illustrating afirst exemplary messaging flow for a method for adjusting radio resourcemanagement procedures in a mobile device operating in a heterogeneouscommunication network, in accordance with exemplary embodiments of thepresent invention, is shown. In one embodiment, UE mobile device 120 andserving eNB 115 send and receive radio resource control (RRC) messages405, 410 to enable the UE mobile device 120 to obtain cell information,including, for example, information relating to one or more of cellsize, cell type, system load, node information, maximum transmit power,maximum base station users, number of antennas and antenna gain, fromthe serving eNB 115. Examples of the different types of cell size andcell type information that may be requested and provided includes cellsizes and types enumerated, for example, in 3GPP2 TS 36.331 and 36.133,and may include very small, small, medium, large, very large, macro,large macro, very large macro, micro, pico and femto cell types and cellsizes. This cell information is then utilized by the UE mobile device120, along with signal reception information, including, for example,information relating to one or more of reference signal received power(RSRP), reference signal received quality (RSRQ), channel qualityindicator (CQI), channel state information (CSI) and signal tointerference plus noise ratio (SINR), to determine whether to adjustradio resource management procedures. For example, in particularembodiments, the mobile device may adjust a handover process utilized bythe mobile device based on the cell information and the signal receptioninformation. In various embodiments, the adjustment may include, forexample, setting the size of a measurement report, setting the value ofmeasurement gap, determining a Time-to-Trigger value, and determining asignal hysteresis value, in the UE mobile device 120 by, for example,adjusting one or more of handover, uplink (UL) power control, radio linkfailure (RLF) recovery and link adaptation. Reference signal receivedpower (RSRP) and reference signal received quality (RSRQ) are described,for example, in 3GPP TS 36.321, and channel quality indicator (CQI) andchannel state information (CSI) are described, for example, in 3GPP TS36.133.

FIG. 5 is a diagram of a radio resource control (RRC) cell informationrequest message for use in a method for adjusting radio resourcemanagement procedures in a mobile device operating in a heterogeneouscommunication network, in accordance with exemplary embodiments of thepresent invention. The diagram 500 illustrates the information elementsthat may be included in the radio resource control (RRC) cellinformation request message 405 sent from the UE mobile device 120 tothe serving eNB 115, as shown in the time sequence diagram 400illustrated in FIG. 4.

FIG. 6 is a diagram of a radio resource control (RRC) cell informationresponse message for use in a method for adjusting radio resourcemanagement procedures in a mobile device operating in a heterogeneouscommunication network, in accordance with exemplary embodiments of thepresent invention. The diagram 600 illustrates the information elementsthat may be included in the radio resource control (RRC) cellinformation response message 410 sent from the serving eNB 115 to the UEmobile device 120, as shown in the time sequence diagram 400 illustratedin FIG. 4.

Referring now to FIGS. 7 and 8, flow charts illustrating a method foradjusting radio resource management procedures in a mobile deviceoperating in a heterogeneous communication network using radio resourcecontrol (RRC) cell information request and response messages, inaccordance with exemplary embodiments of the present invention, areprovided. In the flow chart of FIG. 7, the steps are being performed bythe UE mobile device 120. In the flow chart of FIG. 8, the steps arebeing performed by the serving eNB 115.

Referring first to FIG. 7, in the first step 705, the UE mobile device120 transmits a first message to the serving eNB 115. The first messagemay be a radio resource control (RRC) cell information request messageincluding a request for cell information. As described above, the cellinformation requested from the serving eNB 115 may include, for example,information relating to one or more of cell size, cell type, systemload, node information, maximum transmit power, maximum base stationusers, number of antennas and antenna gain.

Referring now to FIG. 8, in the first step 805, the serving eNB 115receives the first message from the UE mobile device 120 requesting thecell information. In step 810, the serving eNB 115 measures a valuerelating to received signal strength, and then, in step 815, transmits asecond message to the UE mobile device 120 only when the measured valueis greater than a predetermined threshold value. The second message maybe a radio resource control (RRC) cell information response message thatincludes the requested cell information.

Referring now back to FIG. 7, in step 710, the UE mobile device 120receives the second message transmitted from the serving eNB 115, whichincludes the requested cell information. In step 715, the UE mobiledevice 120 measures signal reception information. As discussed above,the signal reception information may include information relating to oneor more of reference signal received power (RSRP), reference signalreceived quality (RSRQ), channel quality indicator (CQI), channel stateinformation (CSI), and signal to interference plus noise ratio (SINR).In step 720, the UE mobile device 120 processes the received cellinformation and measured signal reception information to determine anadjustment to a radio resource management procedure, and in step 725,the UE mobile device 120 adjusts the radio resource management procedurebased on the determined adjustment. As described above, adjusting theradio resource management procedure may include adjusting one or more ofhandover, uplink (UL) power control, radio link failure (RLF) recoveryand link adaptation. In particular embodiments that adjust the handoverprocedure, the adjustment may include, for example, one or more ofsetting the size of the measurement report, setting the value ofmeasurement gap, determining a Time-to-Trigger value, and determining asignal hysteresis value.

As described above, the UE mobile device 120 transmits a first messageto the serving eNB 115. There are a number of different triggeringevents, for example, that may trigger the UE mobile device 120 totransmit the first message, including when the UE mobile device 120enters a new cell, when the state of the UE mobile device 120 changes toconnected mode from idle mode, when the UE mobile device 120 detectsthat it is not operating in a normal (i.e., macro) cell, when referencesignal received power (RSRP) is above a threshold value (e.g., −80 dBm),and when the state of the UE mobile device 120 changes from DTX or DRXsleep mode to active mode.

As also described above, the UE mobile device 120 processes the receivedcell information and measured signal reception information to determinean adjustment to a radio resource management procedure. As alsoindicated above, adjusting the radio resource management procedures mayinclude setting the size of a measurement report, setting the value ofmeasurement gap, determining a Time-to-Trigger value and determining asignal hysteresis value. In another exemplary embodiment, the cellinformation received from the serving eNB 115 includes the cell size andthe signal reception information measured by the UE mobile device 120includes reference signal received power (RSRP) and signal tointerference plus noise ratio (SINR). The UE mobile device 120, inprocessing the received cell information and measured signal receptioninformation, determines if the cell size is large and if the RSRP/SINRvariation is large. If the cell size is not large, then the size of themeasurement report is set to large, and the Time-to-Trigger and signalhysteresis values are set to slow. If the RSRP/SINR variation is notlarge, then the size of the measurement report is set to large, and theTime-to-Trigger and signal hysteresis values are set to slow. If thecell size is large and the RSRP/SINR variation is large, then the sizeof the measurement report is set to small, and the Time-to-Trigger andsignal hysteresis values are set to fast. By determining whether anadjustment to the radio resource management procedure is necessary andmaking the adjustments to the measurement report size, Time-to-Triggervalue and signal hysteresis value, the handover failure rate is reduced.

In another exemplary embodiment, the received cell information includesinformation relating to cell size and system load, the radio resourcemanagement procedure includes setting the size of a measurement reportfor transmission to the node, and, based on the cell size and systemload, the size of the measurement report is adjusted to a standard sizeor a minimum size.

In yet another exemplary embodiment, the mobile device adjusts an RLFrecovery procedure utilized by the mobile device based on the cellinformation and the signal reception information. As one example, themobile device may use information on cell size, and possibly othersuitable considerations (e.g., knowledge of its own speed), in selectinga cell in which to perform RLF recovery. For example, when choosing acell in which to perform RLF recovery, a slow-moving mobile device mayselect a smaller cell for RLF recovery over a bigger cell from which themobile device is receiving a signal of equal or comparable signalstrength. Likewise, a fast-moving mobile device may select a bigger cellfor RLF recovery over a smaller cell from which the mobile device isreceiving a signal of equal or comparable signal strength.

In yet another exemplary embodiment, the mobile device adjusts a linkadaptation procedure utilized by the mobile device based on the cellinformation and the signal reception information. As one example, themobile device may use information on cell size, and possibly othersuitable considerations (e.g., knowledge of its own speed), to determinehow often reference signals, channel state information, or otherinformation associated with link adaptation should be communicated. Forinstance, a mobile device may transmit sounding reference symbols orchannel status information (such as Channel Quality Indicators (CQI))less frequently when operating in a small cell than the relevant mobiledevice would if operating in a large cell. This may result in lowersignaling overhead in the cell and reduced power consumption for themobile device. As another example, a mobile device may also use cellsize to adjust its process for choosing a modulation and coding scheme(MCS). For instance, if a mobile device determines it is operating insmall cell, the mobile device may select more aggressive MCS settingsbased on an assumption that the mobile device is not power limited whenoperating in a small cell. As a result, the mobile device may be able toachieve greater data throughput by virtue of the more aggressive MCSsettings.

In yet another exemplary embodiment, the mobile device adjusts a powercontrol procedure utilized by the mobile device based on the cellinformation and the signal reception information. As one example, themobile device may use information on cell size to determine a specifictransmission power to use. For instance, if a mobile device determinesit is operating in a small cell, it may increase its transmission powerbased on the assumption that the mobile device is not power limited whenoperating in a small cell. As another example, the mobile device mayadjust its procedure for determining an appropriate transmission powerlevel based on the cell information and signal reception information.For instance, the mobile device may, in response to power controlcommands from the network, increase its transmission power by largersteps sizes than it would in response to receiving the same commandswhen operating in a large cell (based again on the assumption that themobile device is not power-limited when operating in a small cell).Because the mobile device can correctly determine it may utilize highertransmission power levels in these scenarios, it may be able to achievemore robust data transmissions and/or greater data throughput.

Referring now to FIG. 9, a time sequence diagram 900 illustrating asecond exemplary messaging flow for a method for adjusting radioresource management procedures in a mobile device operating in aheterogeneous communication network, in accordance with exemplaryembodiments of the present invention, is shown. In one embodiment, UEmobile device 120 and serving eNB 115 send and receive radio resourcecontrol (RRC) messages 905, 910 to enable the UE mobile device 120 toobtain cell information, including, for example, information relating toone or more of cell size, cell type, system load, node information,maximum transmit power, maximum base station users, number of antennasand antenna gain, from the serving eNB 115. This cell information isthen utilized by the UE mobile device 120, along with signal receptioninformation, including, for example, information relating to one or moreof reference signal received power (RSRP), reference signal receivedquality (RSRQ), channel quality indicator (CQI), channel stateinformation (CSI) and signal to interference plus noise ratio (SINR), todetermine whether to adjust radio resource management procedures suchas, for example, setting the size of a measurement report, setting thevalue of measurement gap, determining a Time-to-Trigger value, anddetermining a signal hysteresis value, in the UE mobile device 120 by,for example, adjusting one or more of handover, uplink (UL) powercontrol, radio link failure (RLF) recovery and link adaptation.

FIG. 10 is a diagram of a radio resource control (RRC) connectionrequest message for use in a method for adjusting radio resourcemanagement procedures in a mobile device operating in a heterogeneouscommunication network, in accordance with exemplary embodiments of thepresent invention. The diagram 1000 illustrates the information elementsthat may be included in the radio resource control (RRC) connectionrequest message 905 sent from the UE mobile device 120 to the servingeNB 115, as shown in the time sequence diagram 900 illustrated in FIG.9.

In an exemplary embodiment, the radio resource control (RRC) connectionrequest message may be in accordance with 3GPP TS 36.331, with aninformation element added to indicate a request for cell information,including, for example, information relating to one or more of cellsize, cell type, system load, node information, maximum transmit power,maximum base station users, number of antennas and antenna gain. Forexample, a new information element CellCharacteristicsInfoRequest-IE,with a Boolean value, one bit information, indicating if the cellinformation is requested, may be added:

RCConnectionRequest message -- ASN1START RRCConnectionRequest ::=SEQUENCE {   criticalExtensions   CHOICE {    rrcConnectionRequest-r8        RRCConnection-         Request-r8-IEs,   criticalExtensionsFuture    SEQUENCE { }   } }RRCConnectionRequest-r8-IEs ::=   SEQUENCE {   ue-Identity     InitialUE-Identity,   establishmentCause    EstablishmentCause,  spare   BIT STRING (SIZE (1)) } InitialUE-Identity ::=   CHOICE {  s-TMSI   S-TMSI,   randomValue     BIT STRING (SIZE (40) ) }EstablishmentCause ::=   ENUMERATED {   emergency, highPriorityAccess,mt-Access,               mo-Signalling, mo-Data,  delayTolerantAccess-v1020,   spare2, spare1}CellCharacteristicsInfoRequest-IE ::=   BOOLEAN -- ASN1STOP

FIG. 11 is a diagram of a radio resource control (RRC) connectionresponse message for use in a method for adjusting radio resourcemanagement procedures in a mobile device operating in a heterogeneouscommunication network, in accordance with exemplary embodiments of thepresent invention. The diagram 1100 illustrates the information elementsthat may be included in the radio resource control (RRC) connectionresponse message 910 sent from the serving eNB 115 to the UE mobiledevice 120, as shown in the time sequence diagram 900 illustrated inFIG. 9.

In an exemplary embodiment, the radio resource control (RRC) connectionresponse message may also be in accordance with 3GPP Specification36.331, with an information element added to indicate a request for cellinformation, including, for example, information relating to one or moreof cell size, cell type, system load, node information, maximum transmitpower, maximum base station users, number of antennas and antenna gain.For example, the existing information element CellTypeIE defined in 3GPPTS 36.423 may be added:

RRCConnectionSetup message -- ASN1START RRCConnectionSetup ::=   SEQUENCE {  rrc-TransactionIdentifier    RRC-TransactionIdentifier, criticalExtensions    CHOICE {    c1     CHOICE {    rrcConnectionSetup-r8        RRCConnectionSetup-r8-IEs,     spare7NULL,     spare6 NULL, spare5 NULL, spare4 NULL,     spare3 NULL, spare2NULL, spare1 NULL    },    criticalExtensionsFuture     SEQUENCE { }  }} RRCConnectionSetup-r8-IEs ::=  SEQUENCE { radioResourceConfigDedicated   RadioResourceConfigDedicated, nonCriticalExtension RRCConnectionSetup-v8a0-IEs     OPTIONAL }RRCConnectionSetup-v8a0-IEs ::= SEQUENCE { lateNonCriticalExtension  OCTET STRING      OPTIONAL, -- Need OP nonCriticalExtension     SEQUENCE { }        OPTIONAL -- Need OP }CellTypeIE -- ASN1STOP

Specifically, 9.2.42 of 3GPP TS 36.423 provides the following enumeratedcell sizes, which could be coded by bits, for example: ‘00”=verysmall,‘01’=small, ‘10’=medium, and ‘11’=large:

9.2.42 Cell Type

The cell type provides the cell coverage area.

IE type and Assigned IE/Group Name Presence Range reference Semanticsdescription Criticality Criticality Cell Size M ENUMERATED — —(verysmall, small, medium, large, . . . )

Referring now to FIGS. 12 and 13, flow charts illustrating a method foradjusting radio resource management procedures in a mobile deviceoperating in a heterogeneous communication network using radio resourcecontrol (RRC) connection request and response messages, in accordancewith exemplary embodiments of the present invention, are provided. Inthe flow chart of FIG. 12, the steps are being performed by the UEmobile device 120. In the flow chart of FIG. 13, the steps are beingperformed by the serving eNB 115.

Referring first to FIG. 12, in the first step 1205, the UE mobile device120 transmits a first message to the serving eNB 115. The first messagemay be a radio resource control (RRC) connection request messageincluding a request for cell information. As described above, the cellinformation requested from the serving eNB 115 may include, for example,information relating to one or more of cell size, cell type, systemload, node information, maximum transmit power, maximum base stationusers, number of antennas and antenna gain.

Referring now to FIG. 13, in the first step 1305, the serving eNB 115receives the first message from the UE mobile device 120 requesting thecell information. In step 1310, the serving eNB 115 measures a valuerelating to received signal strength, and then, in step 1315, transmitsa second message to the UE mobile device 120 only when the measuredvalue is greater than a predetermined threshold value. The secondmessage may be a radio resource control (RRC) connection responsemessage that includes the requested cell information.

Referring now back to FIG. 12, in step 1210, the UE mobile device 120receives the second message transmitted from the serving eNB 115, whichincludes the requested cell information. In step 1215, the UE mobiledevice 120 measures signal reception information. As discussed above,the signal reception information may include information relating to oneor more of reference signal received power (RSRP), reference signalreceived quality (RSRQ), channel quality indicator (CQI), channel stateinformation (CSI), and signal to interference plus noise ratio (SINR).In step 1220, the UE mobile device 120 processes the received cellinformation and measured signal reception information to determine anadjustment to a radio resource management procedure, and in step 1325,the UE mobile device 120 adjusts the radio resource management procedurebased on the determined adjustment. As described above, adjusting theradio resource management procedure may include adjusting one or more ofhandover, uplink (UL) power control, radio link failure (RLF) recoveryand link adaptation. Additionally, in certain of the embodiments inwhich the handover procedure is adjusted, the handover procedureadjustment includes one or more of setting the size of the measurementreport, setting the value of measurement gap, determining aTime-to-Trigger value, and determining a signal hysteresis value.

Referring now to FIG. 14, a time sequence diagram 1400 illustrating athird exemplary messaging flow for a method for adjusting radio resourcemanagement procedures in a mobile device operating in a heterogeneouscommunication network, in accordance with exemplary embodiments of thepresent invention, is shown. In one embodiment, serving eNB 115 sends aradio resource control (RRC) message 1405 to UE mobile device 120 toenable the UE mobile device 120 to obtain cell information, including,for example, information relating to one or more of cell size, celltype, system load, node information, maximum transmit power, maximumbase station users, number of antennas and antenna gain, from theserving eNB 115. This cell information is then utilized by the UE mobiledevice 120, along with signal reception information, including, forexample, information relating to one or more of reference signalreceived power (RSRP), reference signal received quality (RSRQ), channelquality indicator (CQI), channel state information (CSI) and signal tointerference plus noise ratio (SINR), to determine whether to adjustradio resource management procedures such as, for example, setting thesize of a measurement report, setting the value of measurement gap,determining a Time-to-Trigger value, and determining a signal hysteresisvalue, in the UE mobile device 120 by, for example, adjusting one ormore of handover, uplink (UL) power control, radio link failure (RLF)recovery and link adaptation.

FIG. 15 is a diagram of a radio resource control (RRC) measurementcontrol message for use in a method for adjusting radio resourcemanagement procedures in a mobile device operating in a heterogeneouscommunication network, in accordance with exemplary embodiments of thepresent invention. The diagram 1500 illustrates the information elementsthat may be included in the radio resource control (RRC) measurementcontrol message 1405 sent from the serving eNB 115 to the UE mobiledevice 120, as shown in the time sequence diagram 1400 illustrated inFIG. 14.

Referring now to FIGS. 16 and 17, flow charts illustrating a method foradjusting radio resource management procedures in a mobile deviceoperating in a heterogeneous communication network using a radioresource control (RRC) measurement control message, in accordance withexemplary embodiments of the present invention, are provided. In theflow chart of FIG. 16, the steps are being performed by the serving eNB115. In the flow chart of FIG. 17, the steps are being performed by theUE mobile device 120.

Referring first to FIG. 16, in step 1605, the serving eNB 115 transmitsa message to the UE mobile device 120. The message may be a radioresource control (RRC) measurement control message including cellinformation. As described above, the cell information transmitted fromthe serving eNB 115 may include, for example, information relating toone or more of cell size, cell type, system load, node information,maximum transmit power, maximum base station users, number of antennasand antenna gain.

Referring now to FIG. 17, in the first step 1705, the UE mobile device120 receives the message transmitted from the serving eNB 115, whichincludes the requested cell information. In step 1710, the UE mobiledevice 120 measures signal reception information. As discussed above,the signal reception information may include information relating to oneor more of reference signal received power (RSRP), reference signalreceived quality (RSRQ), channel quality indicator (CQI), channel stateinformation (CSI), and signal to interference plus noise ratio (SINR).In step 1715, the UE mobile device 120 processes the received cellinformation and measured signal reception information to determine anadjustment to a radio resource management procedure, and in step 1720,the UE mobile device 120 adjusts the radio resource management procedurebased on the determined adjustment. As described above, adjusting theradio resource management procedure may include adjusting one or more ofhandover, uplink (UL) power control, radio link failure (RLF) recoveryand link adaptation. Additionally, in certain of the embodiments inwhich the handover procedure is adjusted, the handover procedureadjustment includes one or more of setting the size of the measurementreport, setting the value of measurement gap, determining aTime-to-Trigger value, and determining a signal hysteresis value.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Thus, the breadth and scope of the present disclosure shouldnot be limited by any of the above-described exemplary embodiments.Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the disclosure unlessotherwise indicated herein or otherwise clearly contradicted by context.

Additionally, while the methods described above and illustrated in thedrawings are shown as a sequence of steps, this was done solely for thesake of illustration. Accordingly, it is contemplated that some stepsmay be added, some steps may be omitted, the order of steps may bere-arranged, and some steps may be performed in parallel.

What is claimed is:
 1. A method for adjusting resource management procedures in a mobile device communicating with a node operating in a cell in a heterogeneous communication network, the method comprising: receiving, by the mobile device, a message transmitted from the node, the message including cell information; measuring, by the mobile device, signal reception information; processing, by the mobile device, the received cell information and measured signal reception information to determine an adjustment to a resource management procedure; and adjusting, by the mobile device, the resource management procedure based on the determined adjustment, wherein the resource management procedure is a radio resource management procedure, wherein adjusting the radio resource management procedure includes adjusting one or more of handover, uplink (UL) power control, radio link failure (RLF) recovery and link adaptation, wherein adjusting handover includes one or more of setting the size of a measurement report, setting a value of a measurement gap, determining a Time-to-Trigger value, and determining a signal hysteresis value, wherein the received cell information includes information relating to cell size and system load, the radio resource management procedure includes setting the size of a measurement report for transmission to the node, and wherein, based on the cell size and system load, the size of the measurement report is adjusted to a standard size or a minimum size.
 2. The method of claim 1, wherein the message is a radio resource control (RRC) measurement control message.
 3. The method of claim 1, wherein the cell information includes information relating to one or more of cell size, cell type, system load, node information, maximum transmit power, maximum base station users, number of antennas and antenna gain.
 4. The method of claim 1, wherein the signal reception information includes information relating to one or more of reference signal received power (RSRP), reference signal received quality (RSRQ), channel quality indicator (CQI), channel state information (CSI), and signal to interference plus noise ratio (SINR).
 5. A mobile device operable in a heterogeneous communication network to transmit messages to and receive messages from a node operating in a cell, comprising: a processor; a memory coupled to the processor; a transceiver coupled to the processor; and an antenna coupled to the transceiver configured to transmit and receive messages; wherein the processor is configured to: receive a message transmitted from the node, the message including cell information; measure signal reception information; process the received cell information and measured signal reception information to determine an adjustment to a resource management procedure; and adjust the resource management procedure based on the determined adjustment, wherein the resource management procedure is a radio resource management procedure, wherein adjusting the radio resource management procedure includes adjusting one or more of handover, uplink (UL) power control, radio link failure (RLF) recovery and link adaptation, wherein adjusting handover includes one or more of setting the size of a measurement report, setting a value of a measurement gap determining a Time-to-Trigger value, and determining a signal hysteresis value, wherein the received cell information includes information relating to cell size and system load, the radio resource management procedure includes setting the size of a measurement report for transmission to the node, and wherein, based on the cell size and system load, the size of the measurement report is adjusted to a standard size or a minimum size.
 6. The mobile device of claim 5, wherein the message is a radio resource control (RRC) measurement control message.
 7. The mobile device of claim 5, wherein the cell information includes information relating to one or more of cell size, cell type, system load, node information, maximum transmit power, maximum base station users, number of antennas and antenna gain.
 8. The mobile device of claim 5, wherein the signal reception information includes information relating to one or more of reference signal received power (RSRP), reference signal received quality (RSRQ), channel quality indicator (CQI), channel state information (CSI), and signal to interference plus noise ratio (SINR). 